Martin Hassellöv detects invisible particles in the ocean

Martin Hassellöv is Professor of Analytical Environmental Chemistry at the Department of Marine Sciences. Together with his research group, he has conducted several high-profile studies on one of the major environmental problems of our time: the increased presence of microplastics and other invisible but foreign particles in the marine environment.

“Environmental chemistry studies are often at a molecular level, very few research groups study pollution in solid form. But much of today's pollution is solid material, from lost fishing gear to various nanoparticles,” says Martin Hassellöv.

The Marine Environmental Biochemistry Research Group investigates tiny fragments of plastics, paint, and other synthetic materials. How much there is, where it comes from, and how is it dispersed are questions asked.

To find the answers, the researchers collect large quantities of water and sediment samples along Sweden's coasts. The samples are filtered and treated in various ways before the work begins of identifying what the extremely small particles consist of.

Detective work with a specialised microscope

“In order to draw any conclusions about sources and pathways, a chemical characterisation of the particle is needed. It's sort of a detective work, where we use techniques sometimes seen in crime TV series,” says Martin Hassellöv.

And this is where the specialised microscopes are utilised.

“We use different microscopy techniques that can be correlated to each other. Simply put, we place different types of microscope images on top of each other to get as much information as possible.”

Martin Hassellöv explains how each microscope can provide different clues.

“In a light microscope you can see things like colour, shape, and lustre, but it doesn't tell you anything about the characteristics of the material, although you might be able to guess. Examining the same sample with a scanning electron microscope can provide information about elements such as carbon, iron, and so on.”

But when dealing with plastics, you need to know which polymers are involved in order to deduce the origin of the particle.

“Then we have specialised microscopes such as Raman and FTIR spectroscopy to produce a chemical ‘fingerprint’ that can be matched to a reference library.”

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One of three labs in the world

It’s the combination possibility that make Martin Hassellöv's microscope room unique, he explains. For example, there are only three labs in the world that have merged a scanning electron microscope with a Raman microscope, which has opened up completely new possibilities for determining the origin of particles.

“We are constantly striving to advance our technical capabilities. Developing microscopy methods is part of our niche.”

It was with the help of the correlative microscopy technique that Martin Hassellöv and his team were able to expose the severe spillage from the plastics industry in Stenungssund a few years ago. Their investigations in the Askerö fjord disclosed that several tonnes of plastic pellets were released in the ocean every year.

Later, in an acclaimed collaboration with the Swedish National Road and Transport Research Institute (VTI), the group was able to document that car tyres are among the largest sources of foreign particles in the marine environment.

“There is a big difference between different tyres, and it turned out that non-studded winter tyres produced much more particles than studded and summer tyres. Theoretical modelling had previously shown that tyres ‘should be’ among the largest sources, but experimental studies were lacking. No one had studied this before.”

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Societal commitment is important

Curiosity and the desire to go in-depth are important driving forces for Martin Hassellöv. He also wants his research to be in demand by society. Therefore, his group has a lot of contact with authorities and has over the years had various assignments for the Swedish Environmental Protection Agency and the Swedish Agency for Marine and Water Management.

“Our results can point to the actions needed. For example, when it comes to tyres, an important conclusion is that better stormwater management is needed to prevent tyre particles from being washed from the roads into the sea when it rains. And that the industry needs to focus more on the wear and tear. In the past, the main focus has been on tyres that are quiet and have good grip.”
 
Martin Hassellöv's commitment to society also extends to the international level. He is co-author of the UN report ‘Second World Ocean Assessment’, and one of the researchers in Gesamp, a UN expert group on marine pollution.

A keen sailor, he is also the initiator of ‘Sailing4Science’, an international network where recreational sailors can contribute various measurements such as temperature, visibility, and algal blooms. The network also supports researchers in developing countries such as Ghana and Tanzania.

“We want to show that many ocean observations can be made even with limited research resources. For example, if you don't have a research vessel, you can do a lot with a sailing fishing boat.”

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From natural particles to synthetic

Martin Hassellöv has his workspace at the Kristineberg Centre, a research station near Fiskebäckskil where the University of Gothenburg is a partner. Growing up in Smögen, not far from Fiskebäckskil, he developed an early interest in the sea, and it was at Kristineberg that he once did his high school work on how copper pollution affects mussels.

When he continued as a doctoral student at the University of Gothenburg, he became interested in natural microparticles such as humus and clay in lakes and rivers. He developed a method to sort the size of very small particles (colloids, or natural nanoparticles) and at the same time measure the metals bound to the particles.

As nanotechnology developed, and the special qualities found in extremely small particles began to be used in sunscreens, pharmaceuticals, self-cleaning windows, and much more, Martin Hassellöv saw an opportunity to move forward:

“The synthetic nanomaterials and their risks were receiving more and more attention, but no one measured or studied them. We already had the methods, and got funding for a large interdisciplinary project to look at risks to natural ecosystems and human health.

About ten years ago, an opportunity rose to move his research to Kristineberg. The family had moved from Gothenburg to the island of Orust, and Martin Hassellöv wanted to get back to study the marine environment.

“I was tired of analysing samples from wastewater treatment plants and dirty urban environments. At about the same time, the enormous amount of microplastics in the ocean was becoming apparent.”

The challenge of contemporary use of plastics

Martin Hassellöv works globally on the plastics issue. He notes that plastic debris today is overflooding beaches and marine areas all over the world, and that poor waste management is often the cause.

“Our use of plastics is a major challenge that will leave a geological imprint on the era we now live in.”

And even though many people are trying to cut down on their use of plastics by using fewer disposable materials and reducing packaging, Martin Hassellöv sees no signs of production decrease - on the contrary, he sees an exponential increase.

“The problem of plastic waste in greater sizes is something tangible that everyone can see, touch, and understand. My research identifies what is a little less tangible, or even invisible. And once plastics has been worn down to microplastics, it cannot be cleaned up. So you have to start working upstream!”

Text: Susanne Liljenström
Translation to English: Annika Wall